Math 2.0

definition

Limit point of a set

Definition

Let SS be a subset of R\mathbb{R} and let aa be a real number. The point aa is a limit point of SS if for each δ>0\delta > 0 there is x∈Sx \in S with 0<∣x−a∣<δ0 < |x - a| < \delta.

Remarks

A limit point of SS need not belong to SS. For example, 00 is a limit point of {1/n:n≥1}\{1/n : n \ge 1\}. Each point of an interval with more than one point is a limit point of the interval. So are its endpoints. Limit points of the domain are the points where the limit of a function makes sense. Mathlib uses the general form AccPt.

Explanations

L1 human

A limit point of SS is a point that we can approach by other points of SS. Points of SS lie as close to it as we like, not counting the point itself.

What this node needs for W2
  • edge instance_of in: one example (0 of 1)
  • edge not_instance_of in: one non-example that fails one clause (0 of 1)

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What depends on this

178 nodes use this node, directly or through other nodes.

Sources

  1. Web https://en.wikipedia.org/wiki/Accumulation_point, Accumulation points of a set